POWER OF ATTORNEY



     KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints J. Mark Merrill,
Laurence Y. Fairey and Richard E. Duerr, Jr., and each of them,
with full power to act without the other, his true and lawful
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any
and all capacities, to sign any and all amendments to the
Registration Statement on Form S-8, and to file the same, with
all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, and each of them, full
power and authority to do and perform each and every act and
thing requisite and necessary fully to all intents and purposes
as he might or could do in person thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of
them, or their or his substitutes or substitute, may lawfully do
or cause to be done by virtue hereof.

DATE:  July 21, 1997                   /s/Marie-Helene Plais
                                       -------------------------
                                       Marie-Helene Plais, M.D.



POWER OF ATTORNEY



     KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints J. Mark Merrill,
Laurence Y. Fairey and Richard E. Duerr, Jr., and each of them,
with full power to act without the other, his true and lawful
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any
and all capacities, to sign any and all amendments to the
Registration Statement on Form S-8, and to file the same, with
all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, and each of them, full
power and authority to do and perform each and every act and
thing requisite and necessary fully to all intents and purposes
as he might or could do in person thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of
them, or their or his substitutes or substitute, may lawfully do
or cause to be done by virtue hereof.

DATE:  July 21, 1997                 /s/Robert A. Compton
                                     ----------------------
                                     Robert A. Compton




POWER OF ATTORNEY



     KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints J. Mark Merrill,
Laurence Y. Fairey and Richard E. Duerr, Jr., and each of them,
with full power to act without the other, his true and lawful
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any
and all capacities, to sign any and all amendments to the
Registration Statement on Form S-8, and to file the same, with
all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, and each of them, full
power and authority to do and perform each and every act and
thing requisite and necessary fully to all intents and purposes
as he might or could do in person thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of
them, or their or his substitutes or substitute, may lawfully do
or cause to be done by virtue hereof.

DATE:  July 21, 1997                   /s/L. D. Beard
                                       ----------------------
                                       L. D. Beard





POWER OF ATTORNEY



     KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints J. Mark Merrill,
Laurence Y. Fairey and Richard E. Duerr, Jr., and each of them,
with full power to act without the other, his true and lawful
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any
and all capacities, to sign any and all amendments to the
Registration Statement on Form S-8, and to file the same, with
all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, and each of them, full
power and authority to do and perform each and every act and
thing requisite and necessary fully to all intents and purposes
as he might or could do in person thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of
them, or their or his substitutes or substitute, may lawfully do
or cause to be done by virtue hereof.

DATE:  July 21, 1997                 /s/George W. Bryan, Sr.
                                     -----------------------
                                     George W. Bryan, Sr.




POWER OF ATTORNEY



     KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints J. Mark Merrill,
Laurence Y. Fairey and Richard E. Duerr, Jr., and each of them,
with full power to act without the other, his true and lawful
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any
and all capacities, to sign any and all amendments to the
Registration Statement on Form S-8, and to file the same, with
all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, and each of them, full
power and authority to do and perform each and every act and
thing requisite and necessary fully to all intents and purposes
as he might or could do in person thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of
them, or their or his substitutes or substitute, may lawfully do
or cause to be done by virtue hereof.

DATE:  July 21, 1997               /s/Yves Paul Cotrel
                                   -----------------------
                                   Yves Paul Cotrel, M.D.




POWER OF ATTORNEY



     KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints J. Mark Merrill,
Laurence Y. Fairey and Richard E. Duerr, Jr., and each of them,
with full power to act without the other, his true and lawful
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any
and all capacities, to sign any and all amendments to the
Registration Statement on Form S-8, and to file the same, with
all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, and each of them, full
power and authority to do and perform each and every act and
thing requisite and necessary fully to all intents and purposes
as he might or could do in person thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of
them, or their or his substitutes or substitute, may lawfully do
or cause to be done by virtue hereof.

DATE:  July 21, 1997               /s/Samuel F. Hulbert
                                   ------------------------
                                   Samuel F. Hulbert, Ph.D.





POWER OF ATTORNEY



     KNOW ALL MEN BY THESE PRESENTS, that each person whose
signature appears below constitutes and appoints J. Mark Merrill,
Laurence Y. Fairey and Richard E. Duerr, Jr., and each of them,
with full power to act without the other, his true and lawful
attorney-in-fact and agent, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any
and all capacities, to sign any and all amendments to the
Registration Statement on Form S-8, and to file the same, with
all exhibits thereto, and other documents in connection
therewith, with the Securities and Exchange Commission, granting
unto said attorneys-in-fact and agents, and each of them, full
power and authority to do and perform each and every act and
thing requisite and necessary fully to all intents and purposes
as he might or could do in person thereby ratifying and
confirming all that said attorneys-in-fact and agents or any of
them, or their or his substitutes or substitute, may lawfully do
or cause to be done by virtue hereof.

DATE:  July 21, 1997               /s/George F. Rapp
                                   --------------------
                                   George F. Rapp, M.D.